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>ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</TITLE
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><H1
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NAME="VIDIOC-G-AUDIOOUT"
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>ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN9692"
></A
><H2
>Name</H2
>VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT&nbsp;--&nbsp;Query or select the current audio output</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN9696"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><P
></P
><A
NAME="AEN9697"
></A
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int ioctl</CODE
>(int fd, int request, struct v4l2_audioout *argp);</CODE
></P
><P
></P
></DIV
><DIV
CLASS="FUNCSYNOPSIS"
><P
></P
><A
NAME="AEN9707"
></A
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int ioctl</CODE
>(int fd, int request, const struct v4l2_audioout *argp);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN9717"
></A
><H2
>Arguments</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><CODE
CLASS="PARAMETER"
>fd</CODE
></DT
><DD
><P
>File descriptor returned by <A
HREF="r14090.htm"
><CODE
CLASS="FUNCTION"
>open()</CODE
></A
>.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>request</CODE
></DT
><DD
><P
>VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>argp</CODE
></DT
><DD
><P
></P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN9737"
></A
><H2
>Description</H2
><P
>To query the current audio output applications zero out the
<CODE
CLASS="STRUCTFIELD"
>reserved</CODE
> array of a struct&nbsp;<A
HREF="r9688.htm#V4L2-AUDIOOUT"
>v4l2_audioout</A
> and
call the <CODE
CLASS="CONSTANT"
>VIDIOC_G_AUDOUT</CODE
> ioctl with a pointer
to this structure. Drivers fill the rest of the structure or return an
<SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
> error code when the device has no audio inputs, or none which combine
with the current video output.</P
><P
>Audio outputs have no writable properties. Nevertheless, to
select the current audio output applications can initialize the
<CODE
CLASS="STRUCTFIELD"
>index</CODE
> field and
<CODE
CLASS="STRUCTFIELD"
>reserved</CODE
> array (which in the future may
contain writable properties) of a
<CODE
CLASS="STRUCTNAME"
>v4l2_audioout</CODE
> structure and call the
<CODE
CLASS="CONSTANT"
>VIDIOC_S_AUDOUT</CODE
> ioctl. Drivers switch to the
requested output or return the <SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
> error code when the index is out of
bounds. This is a write-only ioctl, it does not return the current
audio output attributes as <CODE
CLASS="CONSTANT"
>VIDIOC_G_AUDOUT</CODE
>
does.</P
><P
>Note connectors on a TV card to loop back the received audio
signal to a sound card are not audio outputs in this sense.</P
><DIV
CLASS="TABLE"
><A
NAME="V4L2-AUDIOOUT"
></A
><P
><B
>Table 1. struct <CODE
CLASS="STRUCTNAME"
>v4l2_audioout</CODE
></B
></P
><TABLE
BORDER="0"
FRAME="void"
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><COL
WIDTH="25%"
TITLE="C1"><COL
WIDTH="25%"
TITLE="C2"><COL
WIDTH="50%"
TITLE="C3"><TBODY
VALIGN="TOP"
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>index</CODE
></TD
><TD
>Identifies the audio output, set by the
driver or application.</TD
></TR
><TR
><TD
>__u8</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>name</CODE
>[32]</TD
><TD
>Name of the audio output, a NUL-terminated ASCII
string, for example: "Line Out". This information is intended for the
user, preferably the connector label on the device itself.</TD
></TR
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>capability</CODE
></TD
><TD
>Audio capability flags, none defined yet. Drivers
must set this field to zero.</TD
></TR
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>mode</CODE
></TD
><TD
>Audio mode, none defined yet. Drivers and
applications (on <CODE
CLASS="CONSTANT"
>VIDIOC_S_AUDOUT</CODE
>) must set this
field to zero.</TD
></TR
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>reserved</CODE
>[2]</TD
><TD
>Reserved for future extensions. Drivers and
applications must set the array to zero.</TD
></TR
></TBODY
></TABLE
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN9787"
></A
><H2
>Return Value</H2
><P
>On success <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> is returned, on error <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> and the <CODE
CLASS="VARNAME"
>errno</CODE
> variable is set appropriately:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
></DT
><DD
><P
>No audio outputs combine with the current video
output, or the number of the selected audio output is out of bounds or
it does not combine, or there are no audio outputs at all and the
ioctl is not supported.</P
></DD
><DT
><SPAN
CLASS="ERRORCODE"
>EBUSY</SPAN
></DT
><DD
><P
>I/O is in progress, the output cannot be
switched.</P
></DD
></DL
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